ObjectiveDiffuse midline glioma (DMG), H3K27 altered is a new entity that has become widely recognized. However, studies concerning DMG in adult patients remain rare. We did a retrospective study covering the largest amount of patients to date to analyze the clinicopathological characteristics of diffuse glioma in midline structures of the adult.MethodsWe reviewed 108 cases of adult DMG, collected their clinical data, and pathological results including H3K27 mutation. Summarized their features and the connection with overall survival in different age groups.ResultsAmong 108 cases, 79 tumors were located at the thalamus. 38 patients had H3K27M mutation, whose average age was 35.7 years. The median overall survival of H3K27M-mutant gliomas and the 80 H3K27M wild-type gliomas were both 12 months. For young patients (age ≤ 35), The median survival time of the H3K27M-mutant was 18 months, while that of the H3K27M wild-type was 37 months. For older patients (age>35), the median survival time of the H3K27M-mutant was 16 months, while that of the H3K27M wild-type was 13 months. Other clinicopathological factors including sex, tumor location, the approach of surgery, histological grade, ATRX, and P53 were statistically irrelevant to prognosis.ConclusionThe DMG in adults mainly occurred in the thalamus. H3K27M mutations tend to happen more frequently in young adults, and this genetic alteration results in a worse outcome only in young patients (≤35). For old patients, age is the only independent prognostic factor. Patients who underwent different surgical operations including biopsy, subtotal resection, and total resection had similar prognoses.

Purpose: Diffuse midline glioma (DMG), H3K27M mutant is a new entity that has become widely recognized. However, studies concerning DMG in adult patients remains rare. We did a retrospective study covering the largest amount of patients to date to analyze the clinicopathological characteristics of DMG in adult. Methods: We reviewed 117 cases of adult DMG, collected their clinical and imaging data along with pathological results including H3K27M. Summarized their features and the connection with overall survival in different age groups.Results: Among 117 cases, most tumors were located at the thalamus, 39 patients had H3K27M mutation, of whom 38 demonstrated down regulation of H3K27me3. The average overall survival of H3K27M-mutant gliomas was 13 months, while that of 78 H3K27M wild-type gliomas were 11.8 months. For young patients (age＜35), The median survival time of the H3K27M-mutant was 20.1 months, while that of the H3K27M wild-type was 39.5 months. For older patients (age≥35), the median survival time of the H3K27M-mutant was 22.3 months, while that of the H3K27M wild-type was 17.1 months. The OS of patients who received biopsies, subtotal resections, and total resections were 15.8, 17.6, and 11.6 months respectively. Conclusion: The DMG in adults mainly occurred in the thalamus. H3K27M mutations tend to happen more frequently in young adults, and this genetic alteration results in a worse outcome only in young patients. For old patients, age and the approach of surgery are independent prognostic factors. Patients received biopsy instead of total resection had a better prognosis.

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